Phototube



May 7, 1935. T. H. LONG 2,000,705

' PHOTOTUBE Filed Jan. 17, 1931 WITN ESSES- r INVENTOR v mamas/Huang A'ILTORNEY4 Patented May 7, 1935 UNITED STATES PATENT OFFICE 2,000,705 "PHOTOTUBE I Thomas H. Long, Irwin, Pa., t'o'lwestinghouseElectric & Manufacturing Company,

a corporation of Pennsylvania I I I Application January 17, 1931, Serial Na-soas'n r o icleimsfllci.zap-215i 1 My invention relates tophoto-sensitivedevices sensitive device ofithe type comprising a plurality and has particular relation to photo-sensitive deof independent electrodes; vices of the type adapted to be utilized with sin- Inthe preferredembodiment of my invention, l -phase or plural phase power supply. a single cathode is provided, andla plurality of Photo sensitive devices constructed according anodes are associated with the cathode. 'The 5 to the teachings of the prior art, of which I am cathode is conn'ected to the electrical' 'center'of aware, ordinarily comprise asin'gle cathode anda the D W iIDD Y S H While the anodes are single ano e; when th devi i tiliz d with a connected to the terminals of the source. As a alternating power-supply source, it has a response result, the anodes are maintained at periodic poing Only to the positive half-cycles and, conse 01' a p de l n dafi l quently, supplies the energy in discontinuous For purp s of xpla my nve tio s pulsations. been illustrated as applied to an ordinary alter- In many applications of a photo tube, such as hating-current single-phase power-supply source similar'to that of a halfwave rectifier, respondtentials displaced in phase relative to each other the cinema-acoustic art, it is highly desirable that a d to a t ee-p a I In the former thephoto tube respondcontinuously ,when substance, a single cathode and two anodes are jected to'the infiuenceofan alternating powerutilized; in thelatter'in'stance, a single cathode supply source and to asource of light. Asa matand three anodes a e l i di ter of fact, a difiicult problem has arisen in con app i ation of my invention to the innection with the operation of cinema-acoustic struction-of'atubespecifically Useable for 20 machines in localities I wherein a directcurrent gle-phase Operation, e cathode is in the form of power supplywasnot available by'reason of t a perforated cylinder, and the-anodes are disfact. that the alternating-current power-supply Posed OneiWithln. thecylinder and other causes a rather disagreeablehum to be superim outside of it. The tube'that is adapted tobe utilposed upon the sound transmitte ized with three-phase power is equipped with a Moreover, by reason of the-fact thatthe .ordiperforated (Pathetic having ,tht'ee m naryjube is conductiveonlyduring the time that g; w g 3 gg t halffi'yclesm an 'alternating'cmentl tico; at: 1833311 251? 5.131 3 plysource are impressed between its electrodes in larity in the appended. claims The invgtion 30- Opel 1101mmits'seinsifivityi when it is utilized self however, both as to its organization and its with the alternating-current power-supl ethod 01' operation, together with additional obsource, is considerably smaller than its sensitivjects and changes ther of il t b understood y'w it is utilized With 'd -Q power from the following description of specific embodi- Source- 7 ments, when read'in'connectionwith the accom- Itis, accordingly, an object of my invention to panying' drawin gyln which! provide a photo-sensitive device that shall have a Figure 1 is a view, in transverse section, showi m e s w e subjected to the i flu e inga specific embodiment of a photo tube conof an alternating-curr nt p w -supply s ur strut-ted according to'my invention and adapted 40 Another Obj t my invention is 20 p ov d to be utilized with single-phase altematin'g-cur- 0 aphoto tube adapted to deliver a continuous current power supply; rent when its photo-sensitive elements are sub- Fig. 2. is'a view, in transverse section, illustratjected to the influence of light, and a potential ing a modification of the tubeshown in Fig. 1; from an-alternating-current power supply source F'ig. 3 is, a view, in transverse section, showing is impressed between its electrodes. a further modification of the tube illustrated in i More conciselystated, it is an object of my in- Fig, 1; I vention to provide a photo-sensitive device of a FigAis. a diagrammatic view showing the estype having a plurality of collecting electrodes so sential elements ofthe circuit wherein a tube conrelated to aphoto=sensitive electrode that, when structed according to Fig. 2 is utilized. 50'

the'device is subjected to the influence of a single- Fig. 5 is a view, in transverse section, showing phase or a plural-phase potential, at least one 001- a tube constructed according to my invention and lecting electrode is, at all times, adapted to collect particularly adapted tobe utilized with a threethe' current from the photo-sensitive electrode. phase power-supply. source;

According to my invention, I provide a photo- Fig. 6 is a diagrammatic view illustrating the 55,

3 is adapted to be connected to one terminal of an. "trode photo tube.

alternating-current power-supply source, while the remaining anodes 1 are conductively connect ed and are adapted to be ioined to another terminal' of an alternating-current. power-supply source.

The specific structure of the tube I will be'apparent to one skilled in theartof manufacturing tubes and need not be specifically describedhere In the tube 3 of the type illustrated: in- Fig. 2', the cylindrical cathode is replacedby aplane cathode 9 that is disposed between-a plurality of independent anodes H and; I3. l The tube I4, of the type. illustrated'in 3, has the additional'feature of an internal reflecting surface l5 'so'disposed as to receive the'light that is transmitted through the perforations of the'cathode 9:and to reflect it back to the cathode. It is to be noted that thetube I4 can receive radiations only from the direction? of the unsilvered surface of the; container. 'It2is, furthermore, understood that, in general, the tubesa-re applied' in situations wherein onlya single source of light is available. A tube of the-type. illustrated in Fig. 3 has considerably higher sensitivity thantubes which are not provided with reflecting. surfaces. The apparatus illustrated in Fig- 4 comprises a transformer l1, the-electrical center t9- of the secondary 21 of which isconnec-tedto-the= cathode 9 of a tubev l4 through a load 21- of any type, (such as a mechanical relay or a thermionic amplifier, for example); The anodes il and .13 of the tube are connected to the terminals 33 and l 35 of the secondary 2|. I

It is seen that the anodesl l and l3. of the. tube [4 are continually at potentials of opposite: polarity; if one is. positivejrelatlve to the cathode" 9, the other is negative. As aresult, a pulsating current flows-through the loadassociated with the system. It will .be noted that the'system simulates a push-pull thermionicamplifier. 1 v

The tube 35 of the type illustrated. injFig.5 is equipped with a; cathode 31f comprising a plurality of planesurfaces 39 bounding aplurality of regions wherein the anodes 41, 43 and 415 are disposed. As illustratedqin the view, the tube: 35 isshown as equipped with a. container .41 having-a reflecting surface 49 similar to the containerof the tube l4.

The apparatus shown in Fig. 6 comprises a three-phase line 5| to the terminals 53, 55 and 51 of which the anodes 4|, 43 and of. a tube 35' of the type illustrated in Fig. 5', are connected, and to the electrical center. 61 of which the cathode 37 of the tube is connected, through a load II It will be noted that, as the potentials impressed upon the anodes '59, 6l'and'63 vary, eachanode, in its turn, collects" the current from the cathode 69.

Since the values of positive potential for the anodes 4|, 43 and 45 overlap,-the current supplied by the cathode 31 will, at times, be the sum of the current supplied to two anodes. By reason of this feature, the output of the. system is rendered.

uniform, since, when one anode is decreasing in potential, the second anode is increasing and becomes positive before the former becomes negative. Hence, the increase in the potential of the latter anode tends to compensate for the decrease in the potential of the former anode.

It is understood that, although my invention has its ,most useful applicationsin the, specific form described above and illustrated in the drawing in its most general application, it may be regarded as simply embodied in a plural elec- Fig. 7, a circuit, wherein a tube having a plurality of cathodes and a single anode is utilizedis shown; In the form illustrated in this view, my invention is particularly adapted to be utilized in a bridge network, as shown. .Itisa well known fact that considerable difficulty is encountered in the use of a balanced network system wherein individual photo tubes are disposed in the arms. This difiiculty arises byreason of the fact that the individual photo tubes, being of different structure, have characteristics which vary difierently as a function of time and, consequently, when they are connected in a network, the system cannot be maintained in a permanently stable condition. I

According to -the modification of my invention shown in Fig. 7, a plurality of individual cathodes 13 and 15 aredisposed within a single container 12. As a result of this structure, the essential physical conditions to which the cathodes "and. 15 are continually exposed, are the same. Consequently, when the tube 11 is connected in a bridge-network 19 in such manner that the two ionic paths between the cathodes 13 and 15 and the anode 8| constitute two arms thereof, a balanced system is produced that has permanent response and that need not be readjusted at comparativelyrshort intervals of time. I As shown in Fig. 7, the cathodes 13 and 15 are connected totwo conjugate terminals 83 and 85 of the bridge 19 between which an indicating .in strument 81 is connected. A plurality of variable impedances 89 of requisite type are connected in the remaining arms of the bridge 19, and a power supply source 9'l, illustrated as a battery, is connected between the junction point 93 of the impedance 88 and the anode 8| of the tube 11.

As has been indicated above, my invention has I been shown herein in certain specific embodiments. It has been applied to single-phase and to three-phase systems. It is understood that my invention equally as well applies to plural-phase systems of higher degree than three-phase.

Whilethe principal features of my invention relate to its exercise in connection with tubes of the type having a single cathode and a pluralityof anodes, or to tubes of the type having a single anode and a plurality of cathodes, it is equally well applicable to tubes of the type having a plurality of cathodes and a plurality of anodes, where such tubes prove useful.

Finally, it is well to point out that while, in the embodiments of my invention illustrated in Figs. 1 to 6, the cathodes are shown as perforated, there are certain connections wherein more than one source of light is useable and where, as a consequence, solid cathodes may be utilized. Although'I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior, art and by the spirit of the appended claims.

I claim as my invention:

1. A photo-sensitive device comprising a plurality of collecting electrodes capable of being maintained at independent potentials and a light permeable photo-responsive emitting electrode, said emitting electrode electrically shielding certain of saidcollecting electrodes from certain others of said collecting. electrodes.

2. A photo-sensitive device comprising a cylindrical photo-responsive emitting electrode and at least two collecting electrodes capable of being maintained at independent potentials, one of said collecting electrodes being disposed within said photo-responsive electrode and the other electrode being disposed outside of said photo-responsive electrode, said collecting electrodes being thereby electrically shielded from each other by said photo-responsive electrode.

3. A photo-sensitive device, for use with a pe odic power source having a plurality of terminal taps and an intermediate tap, comprising a plurality of collecting electrodes and a light-permeable photo-responsive emitting electrode, said emitting electrode electrically shielding certain of said collecting electrodes from certain others of said collecting electrodes.

4. A polyphase photo-tube comprising an envelope housing a star-shaped photo-sensitive cathode providing a multiplicity of isolated compartments, each of said compartments containing a cooperative anode to be connected to the tenninals o! a polyphase network.

THOMAS H. LONG. 

